The cannibal-infested remote island in Sons of the Forest offers total sandbox freedom, but following an incorrect cave progression sequence will lead to dead ends and swift demise. Many vital bunkers and underground luxury facilities are locked behind keycards, flooded submerged tunnels, or vertical subterranean chasms. To escape the island and unravel the mystery of the Puffton family, survivors must collect key navigational gear in a strict sequential order.
What this covers: Crucial 4-step cave progression sequence, Rebreather and Rope Gun locations, Shovel excavation requirements, and VIP / Maintenance keycard doors. Why it matters: Exploring the Shovel Cave without already possessing both the Rebreather and Rope Gun physically prevents you from reaching the dig site. Who should pick this: Players wandering aimlessly across the island forest wondering how to open locked security doors.
The Mandatory 4-Step Key Item Route
The underground caverns are locked in a strict dependency chain:
| Progression Step | Target Cave Location | Required Equipment | Crucial Item Unlocked | Unlocks Next Phase |
|---|---|---|---|---|
| Step 1 | Northern Coastline Cave | Flashlight / Torches | Rebreather & Stun Gun | Allows swimming through flooded underwater cave shafts |
| Step 2 | Western Forest Cave | Explosives / Time Bomb | Rope Gun (Zipline) | Allows riding overhead cables across deep cavern chasms |
| Step 3 | Central Mountain Foot Cave | Rebreather + Rope Gun | The Shovel | Allows excavating buried maintenance bunker hatches |
| Step 4 | Maintenance Bunker A | The Shovel | Maintenance Keycard | Opens Food and Dining Bunker and VIP security suites |
Attempting Step 3 without completing Steps 1 and 2 is impossible; the cave entrance requires riding a zipline across an abyss, and exiting requires diving through a flooded underwater cavern.
Cave by Cave: Loot and Threat
The island’s GPS tracks nine marked caves in total, but only four sit on the main progression chain. Knowing what each one drops — and what is waiting inside — prevents a wasted dive.
| Cave | Other Name | Key Loot | Notable Threat |
|---|---|---|---|
| Cave A | Rebreather Cave | Rebreather, Stun Gun | 0–2 Sharks in the flooded chamber |
| Cave B | Rope Gun Cave | Rope Gun, Cross, Artifact Piece C | 1 Sluggy blocking the route |
| Cave C | Shovel Cave | Shovel, Wetsuit, Slingshot, Flashlight Attachment | 2 Legsy, 1 Sluggy, long flooded passages |
| Cave D | Ancient Armor Cave | Ancient Armor, Rifle | Demons and a flooded section |
The Stun Gun shares the Rebreather Cave, resting on the body of a maintenance worker hanging from the ceiling, which is why a single trip north can arm both the dive and the fight.
Fueling the Rebreather: Air Tank Math
The Rebreather does not generate air — it draws from equipped Air Tanks, and the arithmetic decides how long a flooded passage you can risk. One Air Tank delivers roughly 400 seconds of underwater breathing. Four spares carried in the inventory plus the fitted tank total about 2,000 seconds, or 33 minutes and 20 seconds of submerged time.
That budget shrank after launch: the Full Game release patch made air tanks drain 25% faster. Two habits keep the rebreather reliable — check remaining air before entering a passage you cannot surface from, and assign the Rebreather to a hotkey so it toggles without a trip to the inventory. Pairing it with the Wetsuit smooths long underwater stretches once both are collected.
Excavating with the Shovel
Once the Shovel is acquired from the depths of Cave 3, your GPS tracker marks the buried hatch dig sites with Green Pulsing Icons across the surface map—plus a pulsing orange “M” pinpointing Maintenance A once you interact with the laptop inside the Shovel Cave:
- Maintenance Hatch A: Buried beneath a patch of dirt in the northwest forest. Digging out the hatch gives access to the Maintenance Keycard, the Golf Cart Battery, and the Firefighter Axe.
- Maintenance Hatch B: Buried near the lakeshore; contains the Compound Bow, valuable silencers, and the 3D Printer.
- Maintenance Hatch C: Located at the eastern golf course; unlocks the Revolver.
Beyond the Bunkers: Other Shovel Dig Sites
The Shovel opens more than three hatches. Buried structures, marked burial sites, and smaller caches all excavate once it is in hand:
- The grave holding the Shotgun becomes diggable and carries its own dig indicator.
- The Buried Mercenary grave yields a GPS Locator — one of the Team B devices used to mark custom points on the map.
- Digging can also turn up small rocks, and designated dig areas are the only spots where meaningful objects appear.
Getting More Out of the Rope Gun
A zipline is only as useful as its reach, and the Rope Gun now reports both range and whether a surface will accept an anchor. A completed line spans up to 150 meters; for a longer route, attach the first endpoint and carry the unfinished rope to the second rather than stopping short.
Ziplines also move cargo. Logs of any length and stones can ride the line toward the far anchor, which turns a cliff-top forest into a supply line for a lakeside build. Doors and gates cannot be anchors, deployed rope can be recovered and reused, and the Knight V cannot be ridden onto a zipline.
Bunkers, Golden Armor, and the Endgame Gate
With the Maintenance Keycard in hand, you can bypass the locked security glass at the Food and Dining Facility:
- Retrieve the VIP Keycard from the executive office monitoring consoles.
- Travel to the Entertainment Bunker to claim the Guest Keycard—the Luxury Bunker’s keypad entrance was removed in Patch 02.
- Descend into the deep volcanic cavern system to claim the Golden Armor (the Ancient Armor outfit); the cosmetic Gold Mask is a separate item found in a bunker morgue, not beside the armor. The armor initially has a dull bronze finish and must be upgraded using the Armor Plater to unlock the Golden Door inside the Luxury bunker, leading into the Cube dimension for the final 1.0 ending sequence.
The Keycard Network at a Glance
Every keycard is used automatically at compatible readers — you never equip one — and none are consumed, so a collected card keeps opening matching doors. The chain runs:
| Keycard | Found In | Opened By | Unlocks |
|---|---|---|---|
| Maintenance Keycard | Maintenance A | Shovel (buried hatch) | Entertainment Bunker doors |
| VIP Keycard | Food and Dining Bunker | Maintenance Keycard | Secured dining area and onward progression |
| Guest Keycard | Entertainment Bunker | Maintenance Keycard | Two Entertainment doors and the residential bunker |
A second Guest Keycard sits in the residential bunker morgue, and the VIP Keycard’s old role as direct access to the Luxury Bunker ended in Patch 02, when that entrance was reworked.
Inside Maintenance A: What Else to Grab
Maintenance A is the densest single stop on the route, so clear it in one trip. Approach the pulsing orange “M” marker just northwest of the snowy mountain, watching for 2 golf carts with surveying equipment beside a dirt path that crosses a stream, then dig where the Shovel icon appears in the dirt.
Inside, take the icy room first — clear the mutant babies, then pick up the Golf Cart Battery on the left and the Firefighter Axe from its open emergency case at the back shelves, along with Light Bulbs and Solar Panels. The rear apartment adds the Pistol Rail, a Laser Sight, and a note from Hank titled “Attention All”; interacting with the flashing red computer marks the Food Bunker on your map, and the Maintenance Keycard itself sits on the desk in that rear room. Before leaving, the bedroom’s ensuite bathroom holds a body, the book Corporate Line, and a Tuxedo.
How Opening Caves Changes the Surface
Every cave you crack open changes the overland game. Destroying the planks over an entrance lets mutants begin spawning on the surface, and at least 2 mutants respawn near caves each day afterward. Building close to an entrance becomes progressively more dangerous, and creepy takeovers of cannibal villages start once at least one cave is open. Opening the Shovel Cave early, then, trades a shortcut for a permanent increase in surface pressure around your base.